GB648467A - Process for the production of sulphonamides - Google Patents

Abstract

Substituted benzene sulphonamides of the general formula <FORM:0648467/IV (b)/1> wherein R1 and R2 represent hydrogen or alkyl groups and X is an amino group, a carboxylic acylamido group, a nitro, nitroso, phenyl hydrazo, phenyl azoxy or phenyl diazo group, are prepared by treating a compound of the formula <FORM:0648467/IV (b)/2> in which R1 and R2 have the above significance with a benzene sulphonyl halide carrying the desired X substituent, e.g. in the presence of an acid acceptor. When the group X is an acylamido group in the desired product it may be hydrolysed to an amino group; similarly, when X is nitro, nitroso, phenyl hydrazo, phenyl azoxy or phenyl diazo, it may be reduced to an amino group. Suitable starting materials mentioned are para-aminosalicylic acid, an alkyl ester thereof such as the methyl or ethyl ester, or an alkyl ether thereof such as the 2-ethoxy, octyloxy or cetyloxy substituted compounds. Suitable sulphonyl halides mentioned are p-acetylamidobenzene sulphonyl chloride and bromide, p-nitrobenzene sulphonyl chloride and p-phenyldiazobenzene sulphonyl chloride. In the examples amides are prepared by reacting 4-aminosalicylic acid with acetyl sulphanilyl chloride and p-nitrobenzene sulphonyl chloride, 4-amino-2-ethoxy benzoic acid and p-acetamidobenzene sulphonyl chloride, and p-aminoethyl salicylate and p-nitro-benzene sulphonyl chloride; acetamido groups are hydrolysed and nitro groups are reduced to amino groups in the products. Specification 432,353 is referred to. 4-Amino-2-ethoxy benzoic acid is prepared by ethylating p-nitrosalicylic acid, hydrolysing the resulting ester to 4-nitro-2-ethoxy benzoic acid which is reduced.